ASGCE Services

Communication & Civil Work

FTTX-FIBER CABLE LAYING Laying of external main & Branch Ne works lines, Installation of FTTH Fiber Optic Cables, Installation of Cabins and Exchange Systems, Supply, Delivery and installation of Cables, Trench Excavation & Installation of Pipes, Installation of Concrete in excavation, Installation of Warning Tape/Barricades, Drilling & installation of Manholes, Mandrill Pipe Testing after complete reinstatement and Asphalt. Design, Supply and installation of Building Management System (B.M.S) and internal Telecommunication systems Fiber Laying Techniques: Optical fibers are mechanically very different from steel and copper cables, and the techniques for installing them are therefore significantly different. Fibers are not only are extremely brittle, but also elastic to an extent. Fibers must be also be protected from tensile forces (axial), compressive forces and bending.

The long term transmission characteristics of optical fiber depends on the installation procedures used. Fiber laying is a specialized discipline that has to be performed by trained and experience personnel.

Ducting & Trenching: The traditional method of laying optical fibers still used in most developing countries is Ducting and Trenching. This involves creating a trench through manual or mechanized soil excavation.

Trench specifications are normally defined by local authorities and specified for each operator in countries with multiple operators. The trenching process needs careful control to make sure the trench floor does not have any kinks, major bends and is uniform. Ducts are placed in the trenches and fiber is then blown through the ducts with specialized fiber blowers, using water or air. In Air Assisted Fiber Blowing, the blowers use compressed air to push fiber through ducts.

It is standard practice to lay conduits, then draw inner ducts through the conduits, finally blow the fibers through the ducts. A common conduit size is 4 inches (100mm), but 6 inch (150mm) conduits are also available. The size of the inner duct is normally 1.25 inches. It should be noted that fiber cables should never use more than 70% of the available duct space. When 1 inch fiber cables are used, they occupy 64% of a 1.25 inch duct. Ducts are manufactured from High Density Polyethylene (HDPE). HDPE is hard, can withstand temp. up to 120°C and have excellent resistance to alcohols, concentrated acids and bases.

Mini Trenching: This technique can be used on routes that contain asphalt surfaces such as sidewalks and roads. This technique has an advantage over conventional cable laying methods in that it is much faster to execute. The cross-section & depth of the trench will depend on the number of ducts to be laid. While the cross-section varies between 7 to15 cm, the depth between 30 to 40 cm. Three methods of mini trenching commonly used are: Standard, Semi Automated, Fully Automated Trenching, ducting, backfill operations and cleaning are all performed simultaneously when the fully automated method is used. When the standard and semi-automated methods are however employed, the operations are not done at the same time.

Micro Trenching: Micro trenching does not create a creates a shallow trench, typically 2 cm wide and 30 cm deep. Special micro tubes are then placed in the grooves and it is filled, typically with a cold asphalt. The fibers are then blown into the tubes. Aerial fiber cables installation: Aerial fiber optic cables are installed using a technique similar than that used for copper telecommunication cables. It is however important to realize that the transmission characteristics of fiber is affected by compressive stress, tensile stress and bends, making it essential to ensure that cable sag is within acceptable limits.

Messenger or support wires: made from Galvanized Iron (GI) provide support for the fibers strung between GI, or other suitable poles. The lashing of fiber optic cable is done using two methods – the Stationary method and the Moving Reel method. With the Stationary method, the cable is pulled into place using cable blocks, while the Moving Reel method employs reel carrying vehicles on the entire route of the fiber. Cables best suited for aerial installations are All Dielectric Self- Supporting (ADSS) cables. As the name implies, ADSS cables do not need supporting or messenger wires.